Drilling vessel

ABSTRACT

The invention relates to a drilling vessel comprising a drilling tower and a tubular string support structure for supporting a tubular string in the firing line of the drilling tower. The tubular string support structure has two parallel rails and two carts supported by those rails. Both carts have a hanger body with a central passage for supporting a tubular, and each cart can be moved between a central support position for supporting a tubular in the firing line, and a secondary position adjacent the central support position. When both carts are located in their secondary position, the carts are located on opposite sides of the firing line, such that between the carts there is a passage for passing through large objects along the firing line.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of copending application Ser. No.14/894,255, filed on Nov. 25, 2015, which was filed as PCT InternationalApplication No. PCT/NL2014/050337 on May 27, 2014, which claims thebenefit under 35 U.S.C. § 119(a) to Patent Application No. 2010865,filed in Netherlands on May 27, 2013, all of which are hereby expresslyincorporated by reference into the present application.

FIELD OF THE INVENTION

The present invention relates to a drilling vessel, e.g. for oil and gasexploration, well servicing, etc., the drilling vessel comprising adrilling tower having a firing line, along which a tubular string ispassed into the sea during drilling activities, the firing lineextending in a substantially vertical direction.

BACKGROUND OF THE INVENTION

In general drilling vessels are provided with tools and hang of clamps,such as riser spiders and slips, for working on, assembling,disassembling and supporting tubular strings in the firing line of thedrilling tower. The tools and hang of clamps are typically designed towork with a tubulars having a specific diameter. When tubulars of adifferent diameter are to be handled, the tools and of clamps are oftenreplaced with tools and clamps that fit the diameter of the othertubulars. Changing of clamps and tools in the firing line costs time.

OBJECT OF THE INVENTION

The present invention aims to propose solutions to make optimum use ofthe firing line on a drilling vessel.

SUMMARY OF THE INVENTION

According to a first aspect, the invention provides a drilling vessel.

The drilling vessel is provided with two carts on opposite sides of thefiring line. While one cart can is located a the central supportposition for supporting tools and/or a tubular or tubular string locatedin the firing line, the other cart is located in its secondary positionoutside the firing line. Thus, work in the firing line can progressusing the first cart, while the second cart is adapted to performsubsequent activities on the tubular string located in the firing line.The drilling vessel according to the first aspect of the invention thusallows to make optimum use of the firing line on a drilling vessel.

A drilling vessel according to the first aspect of the inventioncomprises a drilling tower having a firing line and a tubular stringsupport structure. Along the firing line of the drilling tower, atubular string is passed into the sea during drilling activities. Thefiring line extends in a substantially vertical direction and passesthrough an elongated opening. The tubular string can be a drillingstring, i.e. a string of drilling tubulars, a casing string, i.e. astring of casing tubulars, etc.

In an embodiment, the elongated opening is provided in a deck,preferably a drilling deck. In a further embodiment the deck in whichsaid elongated opening is provided is the deck that also supports theriser tensioners. In an embodiment, the drilling tower is supported by apart of the hull of the drilling vessel that also supports the deck inwhich the elongated opening is provided. For example, in an embodimentthe drilling tower is supported by cross beams that also support atleast a part of the deck in which the elongate opening is provided, suchthat the bottom end of the tower is located at substantially the sameheight of the deck in which the elongate opening is provided. Thus, whenseen in cross section, the drilling tower does not extend below the deckboth the deck and the drilling tower are supported by the same hullconstruction

The tubular string support structure comprises two parallel rails andtwo carts. The two parallel rails are provided on opposite sides of theelongated opening, such that the firing line of the drilling towerpasses through the elongated opening and between the rails.

It is noted that the rails can be provided in the form of beams that arepart of the construction of the hull, or can be provided in the form ofskid beams or actual rails supported by the hull of the vessel. In anembodiment, the support rails are provided below a top surface of thedeck, preferably the drilling deck, in which the elongated opening isprovided, such that the carts are at least partially recessed in thedeck.

The two carts of the tubular string support structure each have a hangerbody, which hanger body defines a vertical passage adapted to receive atubular string supported in the firing line, for example by a hoistingdevice provide on the drilling tower for lifting and lowering tubulars.The hanger body defines a lateral passage, in communication with saidvertical passage, allowing to place the tubular string in and remove thetubular string from said vertical passage.

The carts are each supported by the parallel rails such that each cartcan be moved between a central support position, above the elongatedopening with the firing line passing through the vertical passage, and asecondary position above the elongated opening with the firing linepassing outside the vertical passage. Furthermore, when both carts arelocated in their secondary position, the carts are located on oppositesides of the firing line, such that between the carts there is a passagefor passing through large objects along the firing line.

In an embodiment, the carts are provided in a recess in a deck, whichrecess also forms the elongated opening in a deck, preferably such thatthe carts are supported such that the top side of the carts issubstantially flush with the top surface of the deck or such that thetop side of the carts is located below the top surface of the deck inwhich the elongate opening is provided. In such an embodiment theelongated opening essentially forms a recess or groove in the deckstructure, in which recess or groove the carts are located. In a furtherembodiment, the carts are provided in a recess in a deck that is locatedabove the elongated opening, and which is preferably dimensionedsubstantially similar to the elongated opening. In an alternativeembodiment, the carts are provided in a recess in the deck that overlapswith the elongated opening. For example, the elongated opening overlapswith the central support position, while the carts in their secondarypositions are located adjacent the elongated opening, when seen in topview.

In a further embodiment, the tubular string support structure isprovided in a deck section which is pivotable or slideable into and outof a position above a moonpool or similar. For example, by providing thetubular support structure in a pivotable deck section, the tubularsupport structure can be removed be pivoting the deck section, forexample into a vertical, upright position, to lift or lower productsalong the firing line which products are to large to be passed betweenthe two parallel rails and/or the carts located in their secondarypositions.

Due to the c-shape of the hanger bodies, i.e. the hanger bodies defininga vertical passage combined with a lateral passage, the carts can bemoved into and out of the central support position while a tubular issupported in the firing line. Thus, a tubular can be supported by atubular string support structure mounted on the tower, for example awinch or a trolley, which tubular string support structure is configuredfor lowering, lifting and supports one or a string of tubulars in thefiring line.

In an embodiment, the firing line is provided on the outside of thetower. It is noted that a drilling tower with one or more firing linesprovided outside the structure of the tower is often referred to as amast type tower. When the firing line is provided outside the tower, theelongate opening in which the two carts are provided is also locatedoutside the confines of the tower. In a preferred embodiment, thedrilling tower is a mast type tower with the firing line located outsidethe mast, and the secondary position of one of the carts is locatedbetween the central support position and the mast.

Preferably, the elongated opening, in which the two carts are provided,has a longitudinal axis that extends in a direction away from thedrilling tower. In such an embodiment, the one cart has a secondaryposition between the central support position and the drilling tower.The secondary position of the other cart is located on the opposite sideof the central support position such that that cart moves away from thetower.

Furthermore, when the vessel is provided with a moonpool, the elongatedopening, in which the two carts are provided, preferably has alongitudinal axis that extends in a direction parallel to a longitudinalaxis of that moonpool.

It is noted that with some drilling vessels, the drilling towercomprises two firing lines, provided on opposite sides of the tower.With such a vessel, the tubular string support structure according tothe invention can be provided at one or at both sides of the drillingtower. In the latter case, each firing line is provided with two cartsaccording for the invention to allow for a quick change of clamps and/ortools. Thus, the drilling vessel according to the invention comprises amast type drilling tower with the firing lines located outside the mastand on opposite sides of the mast. Thus, the present invention alsoprovides an improved multiple firing line drilling vessel. Preferably,with both firing lines, the secondary position of one of the carts islocated between the central support position and the mast.

With a drilling vessel according to the first aspect of the invention,one cart can be located in the central support position for supportingtools and/or a tubular or tubular string located in the firing line,while the other cart is located in its secondary position outside thefiring line. Tools can be mounted on the second cart and/or the secondcart can be adapted for supporting a specific kind of tubular while thatcart is positioned in its secondary position. Thus, work in the firingline can progress using the first cart, while the second cart is adaptedto perform subsequent activities on the tubular string located in thefiring line. Furthermore, the new tools can be positioned in the firingline by simply moving the first cart out of the central support positionand into its secondary position, and moving the second cart into thecentral support position.

In another embodiment according to the invention, both carts comprisethe same type of tool, but each tool is dedicated to a specific type orrange of tubulars. For example, both carts are provided with a tubularsupport device, for example both carts are provided with a tubularclamping device, one of which is dedicated for use with a first type orrange of tubulars, for example tubulars having a first diameter, and theother of which is dedicated for use with a second type or range oftubulars, for example tubulars having a second diameter.

The drilling vessel according to the first aspect of the invention thusallows making optimum use of the firing line on a drilling vessel.

In an embodiment the carts are both provided with a deck surface,preferably substantially level with the deck surface of the deck inwhich the elongated opening is provided, such that the carts each form aslideable deck section, the deck sections preferably having dimensionsof at least 2 by 2 meter, for example 2.5 by 2, 5 meter, more preferablyof at least 3 by 3 meter, for example 4 by 4 meter. Preferably, thecarts thus each form a slideable deck section, which deck sections arepart of the drilling deck of the drilling vessel. Thus, with a tubularstring support according to the invention not only the clamping devicefor supporting the tubular in the firing line is being removed when acart is moved from the central support position to the secondaryposition, but also the drilling deck used by personnel when the cart isin the central support position.

In such an embodiment, not only the hanger body, i.e. the tool formanipulating tubulars or the body supporting tools for manipulatingtubulars is replaced, but also the working deck located around thefiring line.

In an embodiment the tubular support structure comprises a deckstructure and a hanger body provided in that deck body, alternatively,the hanger body can itself form the deck surface or be provided with adeck surface mounted thereon.

In an embodiment, the deck surface of the carts forms the top surfacethereof, and the vertical passage and preferably any actuable supportdevices of the cart are provided below the deck surface of the cart.

Replacing a part of the deck or drill floor instead of only the tools ordevices mounted on the deck or drill floor or in an opening provided inthe deck or drill floor, allows for a quick change of tools and devicesthat can interact with a tubular located in the firing line. Itfurthermore allows for integrating the tools and/or devices, such asclamping devices to be integrated in the deck part, i.e. provided belowthe deck surface of the cart, and thus allow for a free deck surfaceprovides workers with freedom to operate.

By providing the two carts with secondary positions on opposite sides ofthe firing line, adjacent the central support position, the carts candirectly be moved into and out of the central support position, whichallows for a quick change of the carts, and thus of the deck partsprovided on the carts.

In an embodiment, both carts are provided with couple devices forcoupling the carts to each other such that the lateral passages of bothcarts are positioned opposite each other and an object that exits thelateral passage of one hanger body enters the lateral passage of theother hanger body. Thus, moving one cart from the central supportportion into its secondary support position automatically moves theother cart from its secondary position into the support position, and atubular supported in the firing line, for example by a hoisting deviceof the drilling tower, is moved from the central passage of one cartalmost directly into the central passage of the other cart. This allowsfor a quick replacement of the carts located in the central supportposition by the cart located in its secondary position.

In an embodiment, the elongated opening and the two carts aredimensioned such that, when one of the carts is located in the centralsupport position and the other cart is located in its secondaryposition, both carts are located adjacent each other, preferably contacteach other, preferably contact each other such that a deck surfaceprovide on the one cart forms an un interrupted deck surface with thedeck surface provided on the other cart.

Furthermore, by coupling these carts when replacing the cart located inthe central support position with the cart located in its secondaryposition, the deck of the first cart is directly replaced with the deckof the second cart during the transition. No openings, which might causerisk situations for personal, are thus created between the two decksduring the transition.

In an embodiment both carts are configured for performing the samefunction, e.g. supporting a flange of a tubular or clamping thecircumference of a tubular, but differ in the diameter of the tubularthey can handle, for example differ in the diameter of the verticalpassage, such that one cart can be used with tubulars having a firstdiameter and not with tubulars having a second diameter, and the othercart can be used with tubulars having the second diameter and not withtubulars having the first diameter. Such an embodiment can for examplebe used when switching from building a casing string to building adrilling string, which drilling string is with its lower end attached tothe upper end of the casing string, for lowering the casing string intothe drilling hole, which kind of drilling string is also referred to asa landing string. Alternatively, the first cart is configured forhandling a first range of tubulars, e.g. tubulars having a diameterwithin a first range, and the second cart is configured for handling asecond range of tubulars, e.g. tubulars having a diameter within asecond range, which second range does not, or only partially overlapswith the first range. Such can for example be beneficial when building atapering drilling string, i.e. a drilling string composed of thetubulars with reducing diameter when seen from top to tip.

Thus, both carts are dedicated to a specific function, for example areboth provided with extendable slips for engaging and clamping a tubularbody in the firing line to support it, but are each tuned to work withtubular bodies of a specific diameter. Thus, more dedicated tools can beused, while the drawback of time consuming replacing, remounting, andtuning of those tools preventing work being done in the firing line eachtime for example the diameter of the tubulars to be handled changes, canbe avoided.

In an embodiment according to the invention the carts are each supportedby the parallel rails such that when they are located in their secondaryposition, their lateral passages are directed towards the firing line.Thus, the carts are optimally positioned for quickly replacing eachother.

In a further embodiment, the carts, when located in their secondaryposition, are positioned directly adjacent the cart in the centralsupport position, such that an overall compact configuration is achievedin combination with an optimal positioned for quickly replacing one cartlocated in the central support position with the other cart. In afurther embodiment, the carts are coupled, such that when one cart ismoved out of the central support position, the other cart is pulled intothe central support position.

In an embodiment, the carts are configured such that they can be liftedfrom the supporting rails, preferably when located in their secondaryposition, to enable the cart to be replaced with another cart, forexample to be replaced with a cart configured for supporting tubularshaving different dimensions.

In a further embodiment, both carts are at opposite sides of the lateralpassage provided with support sections at their topside, and both cartscan be positioned partially in or adjacent to the central supportposition at the same time, such that the carts can together support anobject, e.g. spider gimbal, located in the firing line.

For example, both carts can be moved from their secondary positiontowards the firing line, such that the distance between the two carts isreduced and both carts are partially located in the central supportposition at the same time, while the firing line passes between bothcarts. Subsequently, an object such as a riser spider is placed in thefiring line such that it's opposite ends are located on the cartspositioned on opposite sides of the firing line. Thus, the cartstogether support the riser spider in the firing line.

In an embodiment, both carts are at opposite sides of the lateralpassage provided with couple devices for cooperating with couple devicesof an object located in the firing line, e.g. a spider gimbal providedwith such couple devices, and wherein both carts can be positionedpartially in or adjacent to the central support position at the sametime, such that the carts can together engage such an object to supportit in the firing line.

In such an embodiment, the side of a cart that faces the other cart isprovided with these coupling means, and the coupling means of therespective carts can be moved towards each other by moving the cartstowards the firing line. Thus, an object such as an intermediateprovided between two tubulars of a tubular spring can be engaged, onopposite sides, by the coupling means of the respective carts. Forexample, the carts can be provided with pins that extend from the carttowards the other cart, and an object located in the firing line can beprovided with recesses for receiving those pins, such that the carts canbe coupled with the object by moving the carts towards the object andthus inserting the pins provided on the carts in the openings proceed inthe sides of the object.

In an embodiment, the hanger body of at least one cart is configuredwith the vertical passage having a diameter wider than the lateralpassage, such that, when seen in top view, the combined vertical passageand lateral passage form a key hole shaped opening. Such a cart ispreferably furthermore provided with grips that can be inserted into thecentral opening to engage a tubular extending through said opening. Forexample, the cart can be provided with recess shaped for receiving andsupporting gripping blocks, which can be placed into said openings toreduce the diameter of the central opening and engage tubular extendingthrough the vertical passage or for supporting the flange of a tubularextending through the central passage. In addition, or as analternative, the cart can be provided with retractable jaws or dogs thatcan be inserted into the vertical passage to support a flange of atubular of a riser string. In an embodiment, at least one cart isconfigured for receiving slips such that the vertical passage can beadapted to the particular cross section of a tubular string.

In an embodiment, at least one cart is provided with three or moreclamping blocks, which clamping blocks are provided along thecircumference of the vertical passage at even intervals such that theycan engage a tubular string passing through said vertical passage, andwhich clamping blocks can be moved in a radial direction with respect toa central axis of the vertical passage, such that tubular strings ofdifferent diameter can be engaged with said clamping blocks.

In a further embodiment, the cart is provided with a vertical guide foreach clamping block, such that the clamping blocks are moveablysupported in the central passage for movement in a diagonal direction,i.e. upward in combination with radially outward and downwards incombination with a radially inward. Thus, the clamping blocks can beused as slips for supporting, and clampingly engaging, a tubular locatedin the vertical passage of the cart.

In a further embodiment, the clamping blocks are provided with pads forengaging the tubular string. Thus the pads can be replaced when wornout, or to fit a particular circumferential shape or dimension of atubular supported in the vertical passage of the cart.

In an embodiment, at least one cart is provided with a closing deviceconfigured for closing the lateral passage, for example is provided witha door that can block the lateral passage, which closing devicepreferably is designed to provide the hanger body with a ring shapedvertical passage when the lateral passage is closed. In such anembodiment, the closing device can be used for converting the c-shapedclamp into a ring shaped support, which in turn allows for an evendistribution of the weight load of the riser string supported by thecart in the central passage thereof.

In an embodiment, the hanger body of at least one cart is provided witha frusto-conical shape, to facilitate interaction with standard slips.

In an alternative embodiment, the hanger body of each cart comprises aframe composed out of multiple frame sections, which frame sectionspreferably are hingeable connected, and wherein one or more framesections of the frame can be pivoted between an open position, in whichthe frame sections form a C-shaped hanger body, and a closing position,in which the pivotable frame sections close the opening of the C-shapedhanger body.

In an embodiment, the hanger body is provided with multiple actuable,preferably hydraulically actuable, support devices, for example movableclamps or movable slips, which support devices can be moved into and outof the vertical passage for engaging a tubular in said vertical passage.

Preferably, the support devices, more in particular the parts forengaging a tubular, can be moved between an active extended position inwhich they extend in the vertical passage for supporting a tubular, anda retracted passive position, in which they allow for passing a tubularthrough the vertical passage in a vertical direction and/or into and outof the vertical passage via the lateral passage. In the latter, theparts for engaging the tubular are located adjacent or in the hangerbody, or the frame that forms the hanger body.

Composing the frame out of multiple frame sections allows for a modularbuild, which is especially beneficial when the frame sections each framesection comprises an actuator device, for example for engaging a tubularlocated in the vertical passage. Thus identical frame sections,preferably combined with identical actuators, can be combined into ahanger body.

In a further embodiment, the support devices are configured such thatthey can be extended in a range of active positions, such that theactive position of the support devices can be adapted to fit thediameter of a tubular in the vertical passage, and the hanger body canthus be used with a range of tubulars, more in particular with tubularshaving a first diameter.

In an embodiment, the tubular string support structure further comprisesa bearing support, the bearing support defining an opening concentricwith the firing line, and which bearing support enables rotating a cartwhen located in the central support position about a vertical axis ofthe vertical passage of that cart. Thus, a tubular, or tubular stringsupported by that cart can be rotated while being supported in thefiring line. The bearing can be a roller type bearing or any other typeof bearing suitable for supporting large loads.

In a further embodiment, the bearing support intersects the two parallelrails, such that the two parallel rails are split into a first and asecond set of parallel rails, each for moving one of the two cartsbetween their secondary position and the central support position, inwhich central support position the carts are located on the bearingsupport with the firing line passing through the vertical passage. Thus,the part of the cart which contacts the rails is moved onto the bearingsupport when the cart is moved into the central support position.

In an embodiment, the carts are skid carts and the rails are providedwith skid surfaces. In such an embodiment, the cart is provided with askid surface, or multiple skid surfaces, with which the cart contactsthe rails. The skid surface can also be configured as a C-shaped skidsurface which C-shape matches the ring shape of the baring support, suchthat the skid surface of the cart, when located on the ring support isfully supported by the ring support.

In a further embodiment, the rails are wide body rails, or even contacteach other such that they form a single skid surface. Such an embodimentprovides a larges support surface area for a cart located in itssecondary position or being moved between its secondary position and thecentral support position. A single wide support surface is especiallybeneficial when the cart is provided with a C-shaped skid surface.

In an alternative embodiment, the carts are rail carts, and are providedwith wheels. In such an embodiment, the rails are configured forproviding a support surface for rolling wheels.

In an embodiment, the bearing support can be removed from the tubularstring support, and the tubular string support furthermore comprises tworail sections that can replace the bearing support when the latter hasbeen removed, bridge the opening between the two sets of parallel rails.Thus, the bearings support can be removed when not needed and bereplaced with rail sections to provide the rails with a continuoussupport surface. This embodiment is especially beneficial when thebearing support intersects the support rails.

It is observed that the ring shaped bearing support defines the maximumdimension of an object to be passed along the firing line through theelongated opening. Furthermore, the ring shaped support prevents a cartform being moved from the central support position into its secondaryposition, or vice versa, while supporting a tubular. Thus, providing abearing support that can temporarily be removed allows for passing alarger variety of objects along the firing line, and for using a cartfor supporting a tubular outside the firing line.

In a further embodiment, the bearing support and the carts are providedwith couple devices for coupling the carts, when located in the centralsupport position, with the bearing support, and wherein the bearingsupport is provided with one or more drives for rotating the bearingsupport and a cart that is coupled therewith. Thus, an optimalrotational support is provided for the cart and, furthermore, thebearing support is used actively turning the cart about a vertical axis.Since the bearing is located below the cart, the drive for rotating thebearing can also be provided below the cart, such that no deck spacedirectly above or adjacent the cart has to be used for mounting a driveto rotate the cart and the bearing.

In a further embodiment, the tubular string support further comprises adiverter, located concentric with the firing line. In an embodiment,beams that form the rails for supporting the cart, or that support thoserails, are also used for supporting the diverter. Thus, the diverter canbe supported directly below the cart supported by the beams, whichallows for a compact configuration of the tubular string support withdiverter.

In a preferred embodiment, the a bearing support is provided on top ofthe diverter, for enabling rotating a cart when located in the centralsupport position about a vertical axis of the vertical passage of thatcart. Thus, the carts can be rotatably supported directly above thediverter, which allows for a compact configuration of the tubular stringsupport with diverter.

In an embodiment, the tubular string support further comprises a carttransport system, which cart transport system comprises one or moretransport devices, such as a hydraulic cylinder or a looped chain orwire, for moving the carts between their secondary position and thesupport position. Thus, there is no need for additional, for exampledeck mounted transporter devices for moving the carts. Preferably, thetransport system is provided below the deck surface of the deck in whichthe elongate opening is provided, and below the top surface of thecarts, which carts in a further embodiment are provided with a decksurface that is substantially flush with the deck surface of the deck inwhich the elongated opening is provided.

In a preferred embodiment, the cart transport system is provided with atransport device on opposite sides of the elongated opening, such that acart is moved by at least two transport devices when being transportedbetween the central support position and its secondary position. Thus,the transport devices can be provided alongside the track, which allowsfor a compact configuration. Furthermore, by engaging both sides of thecart with transport devices, uncontrolled pivoting of the cart about avertical axis during transport can be avoided, which reduces the needfor lateral support of the carts and thus further contribute to acompact configuration of the overall tubular string support.

In an embodiment, the transport system further comprises a yoke for eachcart, the yoke is provided with coupling means for being coupled to theone or more transport devices. The yoke thus forms an interface betweenthe transport devices and the cart, and is for example used for couplingthe transport devices with the cart, but can also be used as a guidingdevice, for example by skidding along the walls of a sloth shaped recessin which the carts are provided, during transport between the secondaryposition and the centrals support position.

Preferably at least the hanger body of the cart is rotatably supportedin the yoke such that at least the hanger body of the cart can berotated, relative to the yoke, about a vertical axis of the verticalpassage of that hanger body.

In an embodiment, the transport devices each comprise a chain or wire,the chains or wires extending on opposite sides of the elongated openingand substantially parallel to the rails of the tubular string supportsystem, and at least one drive for pulling the chains or wires along therails, and wherein each yoke and/or each cart is provided with a coupledevice for coupling the yoke and/or the cart with the chains or wires ofthe transport devices of the transport system.

Thus, the transport devices can be used for transporting both carts. Thecart to be transported is coupled with the transport devices, forexample the yoke of the carts can be provided with hooking device forcoupling the yokes with a chain of the transport device, the chainextending along the support rails. When the yoke is coupled on oppositesides to the chains of the transport devices, the chains can be pulledalong the rails to move the yoke and thus the cart. When a cart is thusmoved into its secondary position, the yoke can be uncoupled from thetransport devices, and the yoke of the other cart can be coupled withthe transport devices to enable the other cart to be moved into thecentral support position.

In a preferred embodiment, the wires or chains are looped around drivensprockets, wheels, winches, or similar located at the ends of the rails.In such a configuration, actuating the sprocket, wheel or winch causes asection of the chain to move along the rail in a first direction, and asection of the chain to move along the rail in the opposite direction.Thus, there is no need for adjusting the direction of rotation of thedriven sprocket, wheel or winch depending on the intended direction oftravel of the cart.

In an alternative embodiment, the transport system comprises transportdevices on opposite sides of the firing line, and the transport deviceseach comprise a cylinder. The cylinders extend on opposite sides of theelongated opening and substantially parallel to the rails of the tubularstring support system. In a further embodiment, each cylinder is coupledwith one end to the yoke of one of the two carts and with an oppositeend to the yoke of the other of the two carts. Each yoke and/or eachcart is furthermore provided with a couple device for coupling the yokeand/or the cart to a frame of the transport system to secure the cart inthe secondary position. Since the cylinders are connected with one endto the yoke of one cart and with their opposite end to the yoke of theother cart, the carts can be moved relative to other using thecylinders. Thus, when a first cart is secured in its secondary position,the second cart can be moved relative to the first cart between thecentral support position and its secondary position. Thus, thisembodiment allows for efficient use of cylinders for moving both carts.

In an alternative embodiment, the transport devices each comprise twocylinders, one for each cart, the pairs of cylinders extending onopposite sides of the elongated opening and substantially parallel tothe rails of the tubular string support system, and wherein eachcylinder is coupled with one end to a frame of the transport system andwith an opposite end to a yoke. Thus each cart is provided with adedicated pair of cylinders, which allows for moving both cartsindependent of each other and at the same time.

Depending on the transport devices used, the coupling between yoke andthe transport devices can be semi permanent. For example, when the sametransport devices are used for moving the first cart and the secondcart, the couple devices can be coupled with the transport devices onlywhile the cart is being transported moved or the can be uncoupled whenthe other cart is moved.

In an embodiment, at least one cart is configured for supporting toolsfor working on a tubular string supported in the firing line, and canmove these tools into and out of a working position by moving betweenthe central support position and the secondary position.

In an embodiment, the drilling vessel comprises a drilling deck, whichdrilling deck has a drilling deck top surface, and the tubular stringsupport structure is recessed in the drilling deck such that it supportsthe two carts within the drilling deck, just below the drilling deck topsurface. In such an embodiment, the carts are supported by the railssuch that the top side of the carts is located below the top surface ofthe deck in which the elongate opening is provided. In a furtherembodiment, the drilling deck covers the carts when in their secondaryposition. For example, the drilling deck may comprise a removable decksection, which covers the carts when in their secondary position, andwhich temporarily be removed to provide access to one or both the cartwhen in their secondary position.

In an embodiment, the longitudinal opening in which the carts of thetubular string support structure are provided, is provided in a drillingdeck. In a further embodiment, a drilling vessel according to theinvention furthermore comprises a moonpool with a moonpool deck, and thedrilling deck is located above said moonpool deck. In a furtherembodiment, the moonpool has an elongated shape and the carts, whenmoved between their secondary position and the central support position,are moved in a direction parallel to a longitudinal axis of themoonpool.

In an embodiment, the longitudinal opening in which the carts of thetubular string support structure are provided, is provided in a drillingdeck, and the drilling vessel is provided with tensioners for supportinga tubular casing string, which tensioners are supported by the drillingdeck. In a further embodiment, according to the invention, the tubularstring support structure further comprises a diverter, which diverter issupported in the firing line, such that a cart located in the firingline is positioned above the diverter.

The invention furthermore provides a method that relates to assemblingand lowering a tubular string comprising tubulars with different crosssections, for example lowering a string of casing tubulars into adrilling hole in the sea bottom using a string of drilling tubulars,drilling tubulars typically having a smaller diameter than casingtubulars. The method comprising the steps of:

-   -   Providing a first cart having a clamping device for engaging the        tubulars with the wide cross section. Thus, tubulars with a wide        cross section can be supported in the vertical passage of the        hanger body of the first cart, and thus in the firing line when        the cart is positioned in the central support position.    -   Providing a second cart having a clamping device for engaging        the tubulars with the narrow cross section. Thus, tubulars with        a narrow cross section can be supported in the vertical passage        of the hanger body of the second cart, and thus in the firing        line when the cart is positioned in the central support        position.    -   Supporting a wide cross section tubular in the firing line using        a hoist system of the drilling tower.    -   Moving the first cart into the central support position and        clamping a wide cross section tubular in the firing line using        the clamping device of the first cart, thus moving the tubular        string, supported by the hoist system of the drilling tower,        through the lateral passage of the hanger body of the first        cart.    -   Clamping the wide cross section tubular in the firing line using        the clamping device of the first cart, and supporting that        tubular in the firing line.    -   Uncoupling the tubular string form the hoist system of the        drilling tower.    -   Attaching another wide cross section tubular to the wide cross        section tubular to form a tubular string. Thus, by subsequently        combining tubulars, or sub sets of two or three already        connected tubulars, to each other a tubular string is assembled.    -   Releasing the tubular string with the clamping device of the        first cart.    -   Lowering the tubular string using a hoist system of the drilling        tower.    -   Engaging the top end of the tubular string with the clamping        device of the first cart and supporting the tubular in the        firing line.    -   Uncoupling the tubular string form the hoist system of the        drilling tower    -   Attaching a narrow cross section tubular to the wide cross        section tubular of the tubular string supported in the firing        line.    -   Coupling the tubular string to the hoist system of the drilling        tower.    -   Releasing the tubular string with the clamping device of the        first cart.    -   Lowering the tubular string using the hoist system of the        drilling tower, and supporting the tubular string in the firing        line using the hoist system of the drilling tower.    -   Moving the first cart out of the central support position and        into its secondary position, thus moving the tubular string,        supported by the hoist system of the drilling tower, through the        lateral passage of the hanger body of the first cart.    -   Moving the second cart from its secondary position into the        central support position, thus moving the tubular string,        supported by the hoist system of the drilling tower, through the        lateral passage of the hanger body of the second cart.    -   Engaging the upper end of the tubular string with the clamping        device of the second cart and supporting the tubular string in        the firing line.    -   Uncoupling the tubular string form the hoist system of the        drilling tower.    -   Attaching another narrow cross section tubular to the tubular        string.    -   Coupling the tubular string to the hoist system of the drilling        tower.    -   Releasing the tubular string with the clamping device of the        second cart.    -   Lowering the tubular string using the hoist system of the        drilling tower, and supporting the tubular string in the firing        line using the hoist system of the drilling tower.    -   Engaging the upper end of the tubular string with the clamping        device of the second cart.        With a method according to the invention, two carts are        provided. One is used for supporting a section of a tubular        string with a wide diameter and the other is used for supporting        sections of that tubular string having a narrow diameter. Thus,        when there is a change in diameter of the tubulars used for        composing the tubular string, the cart in the central support        position is simply replaced by the other cart. The time need for        providing the dedicated tubular support device is reduced and        there is no need for extensive adaptation and or replacement of        tools in the firing line. Thus the work in the firing line is        not, or only for a reduced amount of time, interrupted.

According to the invention a similar method can be used for assemblingor disassembling a string of tubulars comprising tubulars having a firstdiameter and tubulars having a second diameter, wherein the tubularshaving the first diameter alternate with tubulars having the seconddiameter. Other configurations of tubular strings comprising tubularswith different diameter can also be efficiently assembled ordisassembled using a drilling vessel according to the invention.

In a further embodiment according to the invention, instead of aclamping device a supporting device can be used for supporting a tubularby its flange. Typically, such supporting devices are also configured tofit the diameter of the tubular to be supported.

In a further method according to the invention, one cart is providedwith a clamping device for engaging the circumferential surface of atubular body, and the other cart is provided with a supporting devicefor supporting a tubulars by there flange. For example tubulars forcomposing a riser string are typically provided with bouncy means onthere circumferential surface, and are therefore preferably supported bytheir flanges.

In an embodiment, the tubular string support structure is furthermoreconfigured for supporting at least one auxiliary device, for example adiverter and/or a bearing support, at the central support position, suchthat the auxiliary device is supported below a cart located in thecentral support position, and which at least one auxiliary devicepreferably can be lowered into said position and can be lifted out ofsaid position when the carts are both in their secondary position.

In a preferred embodiment, the tubular string support comprises a frame,the frame connecting, and in use supporting, at least the two parallelrails such that the tubular string support. In a further embodiment, theframe may also connect, and in use support, a bearing support and/or acart transport system. Thus, by providing a frame that connects severalcomponents of the tubular strong support and in use supports thosecomponents and the carts, the invention provides a module forretrofitting in existing drilling vessels to provide a drilling vesselaccording to the invention. The modular configuration facilitatesinstalling, and may be fitted such that it can later be easily removedfor example for maintenance.

According to a second aspect the invention furthermore provides adrilling vessel having a firing line, along which a tubular string ispassed into the sea during drilling activities, the firing lineextending in a substantially vertical direction, and a tubular stringsupport structure. According to the second aspect of the invention, thetubular string support structure comprises a cart that can be moved intoand out of a position in the firing line, and a support bearing forsupporting the cart in its position in the firing line and enablingrotation of the cart about a vertical axis of its vertical passage, thevertical axis coinciding with the firing line.

The drilling vessel according to the second aspect of the inventioncomprises:

-   -   A drilling tower having a firing line, along which a tubular        string is passed into the sea during drilling activities, the        firing line extending in a substantially vertical direction,        and;    -   A tubular string support structure, the support structure        comprising:        -   a bearing support, the bearing support defining an opening            concentric with the firing line.        -   at least one cart, the cart having a hanger body that            defines a vertical passage adapted to receive a tubular            string supported in the firing line, and which hanger body            defines a lateral passage, in communication with said            vertical passage, allowing to place the tubular string in            and remove the tubular string from said vertical passage;        -   two parallel rails, which rails are provided to support the            cart such that it can be moved between a central support            position, on the bearing with the firing line passing            through the vertical passage, and a secondary position on            the rails with the firing line passing outside the vertical            passage, and wherein the bearing support enables rotating            said cart when in the central support position about a            vertical axis of the vertical passage of said cart.

With a drilling vessel according to a second aspect of the invention, acart is provided which can be moved in a central support position forsupporting tools and/or a tubular or tubular string located in thefiring line. The tubular string support structure is provided with abearing support, the bearing support defining an opening concentric withthe firing line. The bearing support enables rotating said cart when inthe central support position about a vertical axis of the verticalpassage of said cart. Thus, tools mounted on the cart and/or a tubularsupported by the cart can be rotated about the central axis of thefiring line, and thus be positioned relative to for example anothertubular or other tools already located in the firing line.

In an embodiment, the cart thus provides a movable platform for bringingtools into and out of the firing line, and positioning these toolsrelative to the firing line by rotating them about the firing line. Inanother embodiment, the cart provides a removable support for tubularslocated in the firing line, which in combination with the bearingsupport enables rotating a tubular or tubular string in the firing line.In a third embodiment, the cart is adapted for supporting tools as wellas tubulars. In a further embodiment, the cart also forms a decksection.

The drilling vessel according to the second aspect of the invention thusdiffers form a drilling vessel according to the first aspect of theinvention in that the tubular string support structure may comprise asingle cart instead of two carts located in opposite sides of the firingline. However, all features, and related benefits, described withrespect to a tubular string support structure according to the firstand/or third aspect of the invention, can be combined with the tubularstring support according to the second aspect of the invention.

According to a third aspect, the invention furthermore provides adrilling vessel having a firing line, along which a tubular string ispassed into the sea during drilling activities, the firing lineextending in a substantially vertical direction, and a tubular stringsupport structure. According to the third aspect of the invention, thetubular string support structure comprises a cart transport systemconfigured for moving the at least one cart between its support positionin the firing line, and its secondary position outside the firing line.

A drilling vessel according to the second aspect of the inventioncomprises:

-   -   a drilling tower having a firing line, along which a tubular        string is passed into the sea during drilling activities, the        firing line extending in a substantially vertical direction,        and;    -   a tubular string support structure, the support structure        comprising:        -   Two parallel rails, which rails are provided on opposite            sides of an elongated opening, wherein the firing line            passes through said elongated opening between the rails; and        -   at least one cart, the cart having a hanger body that            defines a vertical passage adapted to receive a tubular            string supported in the firing line, and which cart is            supported by the parallel rails such that the cart can be            moved between a support position, above the elongated            opening with the firing line passing through the vertical            passage, and a secondary position with the firing line            passing outside the vertical passage, and    -   a cart transport system, configured for moving the at least one        cart along the two parallel rails between the support position        and the secondary position.

The drilling vessel according to the third aspect of the invention thusdiffers form a drilling vessel according to the first aspect of theinvention in that the tubular string support structure may comprise asingle cart instead of two carts located in opposite sides of the firingline. However, all features, and related benefits, described withrespect to a tubular string support structure according to the firstand/or second aspect of the invention, can be combined with the tubularstring support according to the third aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings

FIG. 1 shows a drilling vessel according to the invention in perspectiveview;

FIG. 2 shows the drilling vessel of FIG. 1 in partial cross section;

FIG. 3 shows in perspective view from above a section of the drillingvessel of FIG. 1 provided with a tubular support structure according tothe invention;

FIG. 4 shows the section of FIG. 3 in perspective view from below;

FIG. 5A shows in top view an embodiment of a cart according to theinvention, the cart being provided with three clamping blocks;

FIG. 5B shows part of the cart of FIG. 5a in cross section, with theclamping block shown in its top as well as in its bottom clampingposition;

FIG. 6A shows in top view alternative embodiment of a cart according tothe invention, the cart being provided with three clamping blocks;

FIG. 6B shows part of the cart of FIG. 6a in cross section, with theclamping block shown in its top as well as in its bottom clampingposition;

FIG. 7 shows in perspective view from above a section of a drillingvessel of FIG. 1 provided with a tubular support structure according tothe invention, the tubular support section comprising two carts whichare both depicted in their secondary position;

FIG. 8 shows the section of the drilling vessel of FIG. 7, with one cartmoved from its secondary position into a central support position;

FIG. 9 shows the section of the drilling vessel of FIG. 8, with the cartin the central support position rotated about the firing line;

FIG. 10 shows the section of the drilling vessel FIG. 7 with the othercart located in the central support position and rotated about thefiring line;

FIG. 11 shows the section of the drilling vessel of FIG. 7 inperspective view from below, showing a support bearing and both carts intheir secondary position;

FIG. 12 shows the section of the drilling vessel of FIG. 7 inperspective view from below, showing a support bearing, one cart in itscentral support position and one cart in is secondary position;

FIG. 13 shows a perspective view of an alternative tubular supportstructure comprising a cart transport system according to the invention,the tubular support structure being provided in a modular design to befit in a vessel similar to the tubular support structure shown in FIG.7-12;

FIG. 14 shows part of the tubular support structure of FIG. 13;

FIG. 15a-f shows the tubular support structure of the FIG. 13 indifferent working positions;

FIG. 16 shows a perspective view of the tubular support structure ofFIG. 13 with an alternative cart transport system; and

FIG. 17 shows a side view of the tubular support structure of FIG. 16.

Further objects, embodiments and elaborations of the apparatus and themethod according to the invention will be apparent from the followingdescription, in which the invention is further illustrated andelucidated on the basis of a number of exemplary embodiments, withreference to the drawings.

DETAILED DESCRIPTION

FIG. 1 shows a drilling vessel 1 according to the invention inperspective view. The drilling vessel shown comprises a drillingdrilling tower 2. The drilling tower is of the mast type and comprisestwo firing lines 4, both on the outside of the mast. One of the firinglines 4 a is located on the side of the mast type drilling tower thatfaces the front of the drilling vessel, and one of the firing lines 4 bis provided on the side of the mast type drilling tower that faces therear of the drilling vessel. At both sides, the mast type drilling toweris provided with a hoisting device 7, comprising a trolley that can bemoved downward and upward along tracks mounted on the outside of themast, to support, lower and lift tubulars in the firing line. Thesetypes of hoisting devices are generally known and therefore notdiscussed in detail herein.

The drilling vessel 1 is provided with a tubular support structure 3according to the invention, which tubular support structure is located adeck level and in on the front side of the mast type drilling vessel.FIG. 2 shows the drilling vessel of FIG. 1 in partial cross section.

It is observed that the FIGS. 1 and 2 are schematic representations of avessel according the invention and only serve to depict the location ofa tubular support structure 3 on the vessel 1. The tubular supportstructure 3 itself is shown in FIGS. 3 and 4.

FIG. 3 shows in perspective view from above a section of the drillingvessel 1 of FIG. 1 provided with the tubular support structure 3according to the invention. FIG. 4 shows the same section of FIG. 3 butnow in perspective view from below.

The section shown comprises the base 8 of the mast like drilling tower2, and a section of a drilling deck 29 in which the tubular supportstructure 3 is provided. In the embodiment shown, the drilling deck 29is located in front of the mast like drilling tower, and extendsalongside the drilling tower to the back of the drilling tower.

The tubular support structure 3 is provided in front of the tower andabove a moonpool in the hull of the drilling vessel. The firing line 4 aof the drilling tower 2 extends in a substantially vertical directionand passes via the tubular support structure 3 into the moonpool of thedrilling vessel 1. Thus, using the hoisting device 7 of the drillingtower, a tubular string can be passed along the firing line 4 a into thesea during drilling activities, and, using the tubular support stringstructure 3 a tubular or tubular string can be supported in the firingline 4 a.

The tubular string support structure comprises two carts 13,14, eachcomprising a hanger body 14,15. Both carts are supported on a set ofparallel rails 11 extending on opposite sides of an elongated opening12. In FIGS. 3 and 4 the carts are each located in a secondary position,or parking position, on opposite sides of a central support position 18.The firing line 4 a passes through the central support position andelongated opening 12 between the rails 11.

When both carts are positioned in their secondary position, between thecarts there is provided a passage for passing through large objectsalong the firing line.

The hanger bodies of the two carts 13,14 each define a vertical passage16 adapted to receive a tubular string supported in the firing line 4 a,and each define a lateral passage 17, in communication with saidvertical passage, allowing to place the tubular string in and remove thetubular string from said vertical passage.

According to the invention, the carts 13,14 of the tubular supportstructure 3 are configured for supporting a tubular in the firing line 4a. When the carts 13,14 are positioned in the central support position18, their vertical passages 16 are aligned with the firing line 4 a,such that a tubular supported in the firing line is located in thevertical passage 16 of the hanger body, and can be engaged by the hangerbody, for example by way of clamps that engage the tubular in a radialdirection and/or by providing a support surface adjacent the tubular tosupport a flange of the tubular.

The carts 13,14 are each supported by the parallel rails 11 such thateach cart can be moved between the central support position 18, in whicha cart is positioned above the elongated opening with the firing linepassing through its vertical passage, and the secondary position 19, inwhich a cart is located above the elongated opening with the firing linepassing outside the vertical passage. The lateral passage 17 of thehanger body allows for the carts to be moved into and out of the centralsupport position while a tubular, or tubular string, is supported in thefiring line. In such a case, the tubular enters the vertical passage ofthe hanger body via the lateral passage.

The drilling vessel shown in FIGS. 1 and 2 the tubular string supportstructure 3 is recessed in the drilling deck 29, such that it supportsthe two carts 13,14 in the drilling deck 29, substantially below the topsurface of the drilling deck. The carts 13,14 are supported by the rails11 such that the top side of the carts is located substantially levelwith the top surface of the deck in which the elongate opening isprovided.

In an alternative embodiment, the carts are supported by the rails suchthat the top side of the carts is located below the top surface of thedeck in which the elongate opening is provided. In a further embodiment,the drilling deck covers the carts when in their secondary position. Forexample, the drilling deck may comprise a removable deck section, whichcovers the carts when in their secondary position, and which temporarilybe removed to provide access to one or both the cart when in theirsecondary position.

In the embodiment shown the carts 13,14 each are provided with asubstantially flat top surface that functions as a deck. The carts thuseach form a slideable deck section, which deck sections are part of thedrilling deck of the drilling vessel.

The moonpool of the drilling vessel 1, not shown in the figures, extendsin a longitudinal direction of the vessel. The drilling deck, in whichthe tubular support section has been provided, is located above themoonpool, and the carts, when moved between their secondary position andthe central support position, are moved in a direction parallel to alongitudinal axis of the moonpool.

Furthermore, in the embodiment shown, the drilling vessel 1 is providedwith tensioners 28 for supporting a tubular casing string, whichtensioners are supported by the drilling deck 29. Thus a casing stringcan be built in the firing line, using the tubular support structure 3according to the invention, and subsequently be lowered into a supportring of the riser tensioner device, for example to support a casingstring that is connected to a well head in de sea floor.

FIGS. 5 and 6 schematically show, in top view and in a sectional crosssection, a cart, similar to the one shown in FIGS. 3 and 4, in moredetail. The carts shown each comprise a hanger body 15 provided withmultiple actuable, preferably hydraulically actuable, support devices.In the embodiment shown, the support devices are provided in the form ofmoveable clamping blocks 22,23, which can be moved into and out of thevertical passage for engaging and releasing respectively a tubular insaid vertical passage. In the embodiment shown, the clamping blocks22,23 are provided with pads 26, 27, shown in FIGS. 5a and 6a , forcontacting a tubular to be engaged in the vertical passage of the hangerbody. The actuators for moving the blocks are not shown in the figures.

In the particular embodiments shown, the clamping blocks 22,23 aresupported in a vertical guide 24,25. More in particular, the clampingblocks 22,23 are, with a slanted contact surface, supported on a slantedcontact surface of the vertical guides such that, by moving the clampingblocks along the slanted guide surface, the substantially verticalcontact surface of the clamping blocks, in the embodiment shown providedwith the pads 26,27, is moved vertically as well as in the radialdirection towards or away from the firing line. Thus, when the clampingblocks engage a tubular in the vertical passage, the weight of thetubular pulls the clamping blocs in a downward direction, which, due tothe slanted surfaces of clamping blocks and guide, forces the clampingblocks inward and thus enhance the grip of the clamping blocks on thetubular. It is observed that the use of slanted surfaces to enhance thegrip is typically used with slips and similar gripping devices.

FIGS. 5a and 6a show the clamping blocks 22,23 in an extend position,engaging a tubular 9,10 located in the firing line 4. FIGS. 5b and 6bdepict the carts in cross section, with the clamping blocks 22′,23′depicted in a lifted passive position and with the clamping blocks 22,23in a lowered and active position. In the lowered active position, theclamping blocks extend in the vertical passage of the hanger body forengaging and supporting a tubular. In their retracted passive positionthe clamping blocks are moved in the radially outward direction, whichallows for passing a tubular through the vertical passage of the hangerbody in a vertical direction and/or into and out of the vertical passagevia the lateral passage.

The wedge shape of the clamping blocks and the slanted interfacesurfaces of the hanger body and the clamping blocks, provide supportdevices that can be extended into a range of active positions, such thatthe active position of the support devices can be adapted to fit thediameter of a tubular in the vertical passage, and the hanger body canthus be used with a range of tubulars.

The clamping blocks 22 of the cart shown in FIG. 5a are dimensioned forengaging a tubular 9 with a first diameter, and the clamping blocks 23of the cart shown in FIG. 6a are configured for engaging tubulars 10with a second diameter, the second diameter being wider than the firstdiameter. In an embodiment a tubular support structure according to theinvention comprises a first cart similar to the one shown in FIG. 5 anda second cart similar to the one shown in FIG. 6. Thus the tubularsupport structure is configured for supporting tubulars having a firstdiameter and for supporting tubulars having a second diameter.

Furthermore, the clamping blocks 22 of the cart shown in FIG. 5a areconfigured for handling a first range of tubulars, in the embodimentshown are dimensioned for handling tubulars having a diameter within afirst range. The clamping blocks 23 of the cart shown in FIG. 6a areconfigured for handling a second range of tubulars, in the embodimentshown are dimensioned for handling tubulars having a diameter with insecond range. In the embodiment shown, the second range partiallyoverlaps with the first range.

The carts of a tubular support structure shown are thus configured forengaging different types of tubulars, in the embodiment shown tubularsthat differ in diameter. Thus, when the type of tubular to be supportedin the firing line changes, for example when in the firing line atubular string is built of tubulars having a different diameter, thecart in the central support position can be replaced with the other cartto thus adapt the tubular support structure to a change in the type oftubular to be supported.

FIGS. 7-12 show a section of a drilling vessel 1 similar to the oneshown in FIGS. 1 and 2, provided with an alternative tubular supportstructure 50 according to the invention. FIG. 7-10 shows a perspectiveview from above of the section of a drilling vessel and the tubularsupport structure 50 according to the invention, and FIGS. 11 and 12,show a perspective view from below of the section of a drilling vesseland the tubular support structure 50.

According to the invention the tubular string support structurecomprises a first cart 53 and a second cart 54, which are supported onparallel rails 51 above an opening 52 in the deck. Similar to thetubular support structure shown FIGS. 4 and 5 the carts are supported ina recess in the deck. The two carts 53,54 are supported by the rails 51such that the top side of the carts is located below the top surface ofthe deck in which the elongate opening is provided. The deck 29comprises deck sections provided on opposite sides of the centralsupport position 58, which deck sections cover the carts when in theirsecondary position, and which can temporarily be removed to provideaccess to one or both the cart when in their secondary position 59. Inthe figures these deck sections have not been depicted to show the cartsin their secondary positions.

Similar to the carts shown in the preceding figures, both carts 53,54comprise a hanger body 55 provided with a vertical passage 56 and alateral passage 57. The hanger bodies are provided with clamping bodies60, similar to the one shown in FIGS. 5 and 6, which are provided in avertical guide 61.

The tubular support structure 50 shown in FIGS. 7-12 differs from thetubular support structure shown in the preceding figures in that it isprovided with support bearing 63 for supporting the hanger bodies 55 inthe central position, which support bearing is provided concentric withthe firing line. In the embodiment shown, the support surface of thesupport bearing 63 overlaps with the rails, thus effectively dividingthe parallel rails 51 in two subset of rails, one set for supporting thefirst cart and another set for supporting the other cart. Furthermore,in the embedment shown, the support bearing 63 is provided with railssections, which support the cart when located in the central supportposition. In an alternative embodiment, the support bearing is providedwith a ring shaped support surface.

Similar to the carts of the tubular support structure shown in the FIGS.3-6, the vertical passage of the carts 53,54 has a central vertical axisthat coincides with the firing line when the cart is located in thecentral support position. In addition, the carts 53,54 of the tubularsupport structure shown in FIGS. 7-12 can be rotated about that centralvertical axis when the carts are located in the central supportposition. Thus, a tubular or tubular string supported by the cart can berotated about its longitudinal axis.

FIG. 8 shows the tubular support structure 50 with the first cart 53moved from its secondary position into the central support position ontop of the bearing support, such that a tubular supported by the cartcan be rotated about its longitudinal axis. It is observed that in thefigures the tubulars are not depicted.

The hanger bodies 55 differ from the ones shown in the preceding figuresin that they are provided with rounded sides. The hanger bodies areprovided with semi-circular sides to enable rotating the hanger bodieswhile being located in a recess in the deck. Furthermore, the hangerbodies are provided with straight sides, such that when in they arepositioned in their secondary position with their lateral opening facingthe firing line, they provide an extra wide opening between the carts.

FIG. 9 the tubular support structure with the first cart rotated about avertical axis central to its vertical passage and coinciding with thefiring line. FIG. 10 shows the tubular support structure 50 with thefirst cart in its secondary position and the second cart 54 located inthe central support position and rotated about the firing line.

FIG. 11 shows the tubular support structure 50 of FIG. 7 in perspectiveview from below, with both carts in their secondary position, similar tothe situation in FIG. 7. FIG. 12 shows the tubular support structure 50of FIG. 7 in perspective view from below, with both carts 53,54 in theirsecondary position, similar to the situation in FIG. 7.

FIG. 12 shows the section of the drilling vessel of FIG. 7 inperspective view from below, with the first cart 53 located on thesupport bearing 63 and the second cart 54 located in its secondaryposition, similar to the situation shown in FIG. 9.

In the embodiment shown in FIGS. 7-12, the elongated opening is providedin a drilling deck 64 which drilling deck also supports the risertensioners 62. In the embodiment shown, the riser tensioner systemcomprises multiple cylinders and guide wheels, which are all supportedby the drilling deck.

FIG. 13 shows a perspective view of an alternative tubular supportstructure 103 comprising a cart transport system 131 according to theinvention. The tubular support structure 103 is depicted without thevessel. In practice it will be mounted in a drilling vessel adjacent thedrilling tower, preferably a mast type drilling tower, such that thefiring line of the drilling tower passes through the tubular supportsystem as has been discussed with respect to the other embodimentsdisclosed herein.

The tubular string support structure 103 is configured similar to theones disclosed in FIGS. 7-12. The tubular support structure comprisestwo parallel rails 111, which rails are provided on opposite sides of anopening 112 through which, when the tubular string support structure ismounted in a vessel, the firing line passes. The tubular supportstructure further comprises two carts 113,114. Each cart has a hangerbody 115. The hanger bodies 115 each define a vertical passage 116adapted to receive a tubular string supported in the firing line, andwhich hanger body defines a lateral passage 117, in communication withsaid vertical passage, allowing to place the tubular string in andremove the tubular string from said vertical passage.

The carts 113,114 are each supported by the parallel rails 111 such thateach cart can be moved between a central support position 118 with thefiring line passing through the vertical passage, and a secondaryposition on opposite sides and adjacent to the central support positionwith the firing line passing outside the vertical passage.

In the embodiment shown, the tubular string support 103 is furtherprovided with bearing support 163 according to the invention, thebearing support defining an opening concentric with the firing line, forrotatable supporting a cart located in the central support position.

Furthermore, the tubular string support 103 comprises a diverter 130,located such that it is concentric with the bearing support 103 and,when the tubular support structure is mounted in a drilling vessel,concentric with the firing line. The bearing support 103 is provided ontop of the diverter 130, to enable rotating a cart located in thecentral support position, the cart for example supporting a drillstring, about a vertical axis of the vertical passage of the hanger bodyof that cart.

The bearing support 103 and the carts 113,114 are provided with coupledevices, in the embodiment shown openings for receiving bolts, to couplethe carts, when located in the central support position, with thebearing support. Thus, the bearing support enables rotating the cart,and also secures the cart in the central support position while it isbeing rotated. It is observed that other connecting devices, such ashydraulically actuated clamps or pins, can also be used for coupling acart with a bearing support according to the invention.

In the embodiment shown, the bearing support 103 is furthermore providedwith drives for rotating the bearing support and a cart that is coupledtherewith. In the embodiment shown, the bearing is provided with acircumferential contact surface for engagement with an electric drive.In alternative embodiments, other types of drives can be used forrotating the bearing and the cart provided thereupon.

The tubular support structure 103 further comprises a frame of which twoframe elements 162 extend on opposite sides of the tubular supportstructure. The frame connects the different components of the tubularsupport structure 103, in the embodiment shown, the rails 111 andtransport system 131. The frame furthermore provides a seat for thediverter and the bearing support, such that these can be mounted to theframe and secured relative to the rails and transport system of thetubular support system. In the embodiment shown, the bearing support andthe diverter can be removed from the tubular string support and replacedwith rail sections, to enable use of the tubular support structurewithout the bearing support and the diverter.

By providing a frame that connects the main components of the tubularsupport structure, the tubular support structure is configured as a unitor module, that can be mounted in a drilling vessel, for example asshown in FIG. 7-12. Providing the tubular support structure with such aframe and thus a modular design, facilitates installing, and optionallyremoving, the tubular support structure in and from a drilling vessel.

FIG. 14 shows part the tubular support structure 103 of FIG. 13 withoutthe two frame elements 162 provided on opposite sides of the tubularsupport structure. Thus, in FIG. 14 part of the cart transport system131 according to the invention is visible.

According to the invention, the cart transport system comprises one ormore transport devices for moving the carts between their secondaryposition and the central support position. In the particular embodimentshown in FIG. 14, the cart transport system 131 comprises a looped chain132 on each side of the track formed by the support rails 111. A tubularstring support system with an alternative car transport system,deploying hydraulic cylinders for displacing the carts, is shown inFIGS. 16 and 17, and will be discussed in more detail later on.

In the embodiments shown, the cart transport systems are provided with atransport device on opposite sides of the opening, such that a cart ismoved by at least two transport devices when being transported betweenthe central support position and its secondary position. The transportdevices each comprise a chain 132, extending on opposite sides of theelongated opening and substantially parallel to the rails of the tubularstring support system. In the embodiment shown, the chains are loopedover sprocket wheels on opposite ends of the tubular support system, atthe ends of the track comprising the parallel rails for supporting thecarts.

The cart transport device further comprises a drive 133 for pulling thechains along the rails. Each cart is provided with a couple device forcoupling the cart with the chains of the transport system. In theembodiment shown, the carts are provided with arms 134 extendingadjacent the chains, and provided with openings for receiving a pin orother coupling devices to attach the arms, and thus the carts, to thechains. Once the cart has been secured to the chains, it can be movesalong the rails by pulling the chains using the china drive 133.

In an alternative embodiment, a further coupling device, for example ayoke, can be used for connecting the cart with the transport devices ofthe transport system. In an embodiment, the transport system comprises ayoke for each cart, and preferably at least the hanger body of the cartis rotatably supported in the yoke such that at least the hanger body ofthe cart can be rotated, relative to the yoke, about a vertical axis ofthe vertical passage of the hanger body of that cart. The yoke is to becoupled with the transport devices, for example a chain extending alongthe rails of the tubular string support structure.

FIG. 16 shows a perspective view of the tubular support structure ofFIG. 13 with an alternative cart transport system 141. FIG. 17 shows aside view of the tubular support structure of FIG. 16. In the embodimentshown, the transport system comprises a yoke 136 for each cart. Theyoke—is a plate shaped table comprising an opening in which the hangerbody of the cart is mounted. The hanger body 115 of each the cart113,114 is rotatably supported in the yoke 136 such that at least thehanger body 115 of the cart can be rotated relative to the yoke, about avertical axis of the vertical passage of the hanger body of that cart.

The transport devices of the transport system are provided on oppositesides of the track formed by the rails 111, and each comprise ahydraulic cylinder 135. The cylinders extend on opposite sides of theelongated opening and extend in a direction substantially parallel tothe rails of the tubular string support system. Each cylinder is coupledwith one end to the yoke of one of the two carts and with an oppositeend to the yoke of the other of the two carts. Thus, the cylinders ofthe transport system can be used to pull the carts towards each other,and to push them away from each other.

Each yoke is furthermore provided with a couple device, not shown in thefigure, for coupling the yoke to the frame of the transport system, orto for example the hull of the vessel, to secure the cart in itssecondary position. Thus, when one yoke is secured in its secondaryposition, the cylinders can be used to move the other yoke, and thus tomove the cart mounted in that yoke between its central support positionand its secondary position.

In an alternative embodiment, the transport devices of the carttransport system each comprise two cylinders. Thus, on each side of thetrack formed by the rails supporting the carts, two cylinders areprovided, one cylinder for each cart. The pairs of cylinders provided onopposite sides of the track and elongated opening of the tubular stringsupport structure each extend substantially parallel to the rails. Eachcylinder is coupled with one end to a frame of the tubular stringsupport structure and with an opposite end to a yoke. Thus, each yoke isprovided with two dedicated cylinders, and can be moved independent ofthe other yoke.

It is observed that a cart according to the invention comprises at leasta hanger body for supporting a tubular or tubular string. The hangerbody can be configured for supporting a tubular or tubular string forexample by engaging the body of the tubular with clamps, or by providinga support surface for the flange of a tubular body. Also, a hanger bodycan be configured for both engaging a tubular using clamps and bysupporting a tubular flange. Preferably, the hanger body is providedwith moveable support devices, for example clamps that can be insertedinto the vertical passage of the hanger body to engage a tubular, ordogs that can be inserted into the vertical passage to provide a supportsurface for supporting the flange of a tubular body. In an embodiment,the hanger body comprises both clamps and dogs, in a further embodiment,dogs and clams are integrated such that the clamps also provide asupport surface for supporting the flange of a tubular. In anembodiment, the hanger body is the cart, and no additional devices areprovided. In such an embodiment, the hanger body is provided with a skidsurface for movement over the rails of the tubular string supportstructure. In an alternative embodiment, the hanger body is providedwith wheels for movement over the rails of the tubular string supportstructure. In a further embodiment, the hanger body is mounted in aframe, for example such that it can be rotated about a central axisthrough its vertical passage in said frame. In a further embodiment, thehanger body is supported in a frame which frame is provided with wheels.Further alternative configurations of the carts of a tubular stringsupport structure according to the invention are also possible withinthe scope of the invention.

In the embodiment shown in FIGS. 13 and 14, the carts 113,114 eachcomprise a hanger body 115 that is similar to the one depicted in FIGS.7-12. FIGS. 15a-15f show the tubular support structure 103 with thehanger body 115 of one cart in different working positions.

FIGS. 15a-c show a cart being moved by the cart transport system intothe central support position for engaging a tubular supported in thefiring line, for example a tubular that is part of a tubular stringsupported by a hoisting device of the drilling tower in the firing line.In FIG. 15d the doors of the hanger body are closed and locked together,for example by inserting a locking pin, to provide a ring shaped supportfor the tubular. In FIG. 15e , the support devices of the hanger bodyare inserted into the vertical passage to engage the tubular. In FIG.15f , the cart has been disconnected from the cart transport system, hasbeen secured to the bearing support, and has subsequently be rotatedabout a central axis of the vertical passage of the hanger body, to thusrotate the tubular supported by the hanger body about its longitudinalaxis. It is observed that when the hanger body of the cart is rotatablysupported in a yoke, which yoke is coupled with the transport devices ofthe transport system, there is no need to disconnect the yoke or cart toenable rotation of the cart, more in particular the hanger body. It isfurthermore observed that the steps shown in FIGS. 15a-15f are similarto the ones shown in FIGS. 7-9, be it that in those figures a differentembodiment of a tubular string support structure according to theinvention has been depicted.

Of the embodiment shown in FIGS. 13 and 14, the hanger body 115 of eachcart comprises a frame composed out of multiple frame sections 137. Thehanger bodies furthermore comprise two frame sections 138 that functionas doors for closing the lateral opening of the hanger body. FIGS. 5a-cshow the hanger body with the doors open, FIGS. 5d-f show the hangerbody with the doors closed. With the doors closed and secured to eachother, the frame of the hanger body is essentially ring shaped, which isbeneficial for supporting the weight of a tubular string engaged in thevertical passage.

The hanger body 115 of the carts 113,114 is furthermore provided withmultiple hydraulically actuable support devices 139. In the embodimentshown the support devices 139 are provided in the form of slip likeclamps that can be moved into and out of the vertical passage 116 forengaging and releasing respectively a tubular in said vertical passage.FIGS. 15a-d show the support devices 139 of the hanger body 115 in theirinactive, retracted position. FIGS. 15 e-f show the support devices 139of the hanger body 115 in their active clamping position.

In an active extended position, in the support devices extend in thevertical passage of the hanger body for supporting a tubular, and aretracted passive position, in which they allow for passing a tubularthrough the vertical passage of the hanger body in a vertical directionand/or into and out of the vertical passage via the lateral passage.

It is observed that for the sake of clarity, no tubular has beendepicted in the Figs. In practice, the active position of the clampingdevices is the position in which the engage the body of the tubular inthe firing line, such that the tubular is supported. This positiondepends on the diameter of the tubular. In the figures, the clampingdevices contact each other, such that there is no room for a tubularbetween them. Thus, when engaging a tubular, the clamping devices willbe positioned in a radially more outward position than the position inwhich they are depicted in these Figs.

Typically, the clamping devices as shown in the embodiment in FIGS.13-15 can be extended into a range of active positions, such that theactive position of the support devices can be adapted to fit thediameter of a tubular in the vertical passage, and the hanger body canthus be used with a range of tubulars.

In an embodiment, the drilling vessel according to the inventioncomprises a mast type drilling tower, with at least one firing linelocated outside the mast type construction, and, according to theinvention, the at least one firing line extends through an opening indeck, which opening is the centre of a central support position and islocated between two secondary positions of the carts, which carts areconfigured to support a tubular or a tubular string in the firing linewhen located in the central support position.

It is noted that a drilling tower, in particular a mast type drillingtower, is typically provided with one or more hoisting devices to lift,lower and support objects, such as tubular strings, for example a casingstring or a riser string, in the firing line of that drilling tower.

From the foregoing, it will be clear to the skilled person, that withinthe framework of the invention as set forth in the claims also manyvariations other than the examples described above are conceivable.

The invention claimed is:
 1. A drilling vessel comprising: a hull; amoonpool; a deck, located over the moonpool, the deck having a topsurface and a recess, wherein the recess forms an elongated opening inthe deck of the vessel, extends in a downward direction from the topsurface of the deck, and provides access to the moonpool below the deck;a drilling tower having a firing line, along which a tubular string ispassed into the sea during drilling activities, the firing lineextending in a substantially vertical direction, wherein the drillingtower extends in an upward direction from the top surface of the deck;and a tubular string support structure which support structure isprovided above the moonpool in the recess in the deck, the supportstructure comprising: two parallel rails provided in the recess onopposite sides of the elongated opening, above the moonpool and belowthe top surface of the deck, wherein the firing line passes through saidelongated opening between the rails; and at least one cart, each carthaving a hanger body that defines a vertical passage adapted to receivea tubular string supported in the firing line, wherein each cart issupported in the recess, above the moonpool and below the top surface ofthe deck by the parallel rails such that each cart can be moved betweena central support position, above the elongated opening with the firingline passing through the vertical passage, and a secondary position withthe firing line passing outside the vertical passage, and a carttransport system, configured for moving the at least one cart in therecess in the deck along the two parallel rails between the supportposition and the secondary position.
 2. The drilling vessel according toclaim 1, wherein each cart is provided with a deck surface, such thateach cart forms a slideable deck section.
 3. The drilling vesselaccording to claim 1, wherein the deck covers the cart when in thesecondary position.
 4. The drilling vessel according to claim 1, whereinthe cart transport system comprises one or more transport devices formoving the cart between the secondary position and the central supportposition, and wherein the transport devices include one of a hydrauliccylinder or a looped chain or wire.
 5. The drilling vessel according toclaim 1, wherein the cart transport system is provided with transportdevices located on opposite sides of the elongated opening, such thatthe cart is moved by at least two transport devices when beingtransported between the central support position and its secondaryposition.
 6. The drilling vessel according to claim 1, wherein the carttransport system further comprises: transport devices, wherein eachtransport devices comprises a chain or a wire, the chains or wiresextending on opposite sides of the elongated opening and substantiallyparallel to the rails of the tubular string support system, and at leastone drive for pulling the chains or wires along the rails, wherein thecart is provided with a couple device for coupling the cart with thechains or wires of the transport devices of the transport system.
 7. Thedrilling vessel according to claim 1, wherein the cart transport systemfurther comprises: transport devices, wherein each transport device eachcomprises a cylinder, the cylinders extend on opposite sides of theelongated opening and extend in a direction substantially parallel tothe rails of the tubular string support system, and wherein eachcylinder is coupled with one end to the cart and with an opposite end toa frame of the tubular string support structure.
 8. The drilling vesselaccording to claim 1, wherein the hanger body further defines a lateralpassage, in communication with said vertical passage, allowing to placethe tubular string in and remove the tubular string from said verticalpassage.
 9. The drilling vessel according to claim 8, wherein the cartis provided with a closing device configured to close the lateralpassage, wherein the closing device is a moveable door that isconfigured to move over the lateral passage to close the lateral passageand provides the hanger body with a ring shaped vertical passage whenthe lateral passage is closed.
 10. The drilling vessel according toclaim 8, wherein the hanger body is provided with multiple supportdevices, and wherein the support devices can be moved between activeextended positions, in which they extend in the vertical passage of thehanger body for supporting a tubular, and a retracted passive position,in which they allow for passing a tubular through the vertical passageof the hanger body in a vertical direction and/or into and out of thevertical passage via the lateral passage.
 11. The drilling vesselaccording to claim 10, wherein the active extended positions are a rangeof positions for accommodating tubulars with varying diameters.
 12. Thedrilling vessel according to claim 1, wherein the at least one cart isprovided with three or more clamping blocks, the clamping blocks areprovided along the circumference of the vertical passage at evenintervals such that they can engage a tubular string extending throughsaid vertical passage, and wherein the clamping blocks can be moved in aradial direction with respect to a central axis of the vertical passage,such that tubular strings of different diameters can be engaged withsaid clamping blocks.
 13. The drilling vessel according to claim 12,wherein the at least one cart is provided with a vertical guide for eachclamping block, such that the clamping blocks are moveably supported inthe vertical passage, and wherein the vertical guide extends in adiagonal direction with respect to the vertical passage such that eachclamping block is moveable in said diagonal direction.
 14. The drillingvessel according to claim 1, wherein the cart transport system furthercomprises a yoke for the at least one cart, and wherein at least thehanger body of a respective cart is rotatably supported in the yoke suchthat at least the hanger body of the respective cart can be rotated,relative to the yoke, about a vertical axis of the vertical passage ofthe hanger body of that cart.
 15. The drilling vessel according to claim1, wherein the tubular string support structure further comprises abearing support, the bearing support defining an opening concentric withthe firing line and the bearing support enabling rotation of the cartwhen located in the central support position, about a vertical axis ofthe vertical passage of the hanger body of the respective cart.
 16. Thedrilling vessel according to claim 1, wherein the tubular string supportstructure further comprises a frame, the frame connecting at least thetwo parallel rails such that the tubular string support can be providedas a module for retrofitting in existing drilling vessels.
 17. Thedrilling vessel according to claim 1, wherein the at least one cartcomprises two carts, wherein each hanger body defines a lateral passage,in communication with said vertical passage, allowing to place thetubular string in and remove the tubular string from said verticalpassage, and wherein, when both carts are located in their secondaryposition, the carts are located on opposite sides of the firing line,such that between the carts there is a passage for passing throughobjects along the firing line.
 18. A drilling vessel comprising: adrilling tower having a firing line, along which a tubular string ispassed into the sea during drilling activities, the firing lineextending in a substantially vertical direction; a drilling deck havinga drilling deck top surface; and a tubular string support structure, thesupport structure comprising: a bearing support, the bearing supportdefining an opening concentric with the firing line; at least one cart,each cart having a hanger body that defines a vertical passage adaptedto receive a tubular string supported in the firing line, and whereinhanger body defines a lateral passage, in communication with saidvertical passage, allowing to place the tubular string in and remove thetubular string from said vertical passage; and two parallel rails, whichrails are provided to support each cart such that it can be movedbetween a central support position, on the bearing support with thefiring line passing through the vertical passage, and a secondaryposition on the rails with the firing line passing outside the verticalpassage, and a cart transport system comprising one or more transportdevices for moving each cart between the secondary position and thecentral support position, wherein the bearing support enables rotationof the entirety of each cart when in the central support position, abouta vertical axis of the vertical passage of the respective cart.
 19. Adrilling vessel comprising: a hull; a deck, the deck having a topsurface and a recess, wherein the recess forms an elongated opening inthe deck of the vessel, and the recess extends in a downward directionfrom the top surface of the deck; a drilling tower having a firing line,along which a tubular string is passed into the sea during drillingactivities, the firing line extending in a substantially verticaldirection, wherein the drilling tower extends in an upward directionfrom the top surface of the deck; and a tubular string supportstructure, which support structure is provided in the recess in thedeck, the support structure comprising: two parallel rails provided inthe recess on opposite sides of the elongated opening and below the topsurface of the deck, wherein the firing line passes through saidelongated opening between the rails; and two carts, each cart having ahanger body that defines a vertical passage adapted to receive a tubularstring supported in the firing line, wherein each cart is supported inthe recess, below the top surface of the deck, by the parallel railssuch that each cart can be moved between a central support position,above the elongated opening with the firing line passing through thevertical passage, and a secondary position with the firing line passingoutside the vertical passage, and a cart transport system, configuredfor moving the two carts in the recess in the deck along the twoparallel rails between the support position and the secondary position,wherein, when both carts are located in their secondary position, thecarts are located on opposite sides of the firing line, such thatbetween the carts there is a passage for passing through objects alongthe firing line, wherein the cart transport system is provided withtransport devices located on opposite sides of the elongated opening,and each cart can be moved by the transport devices, which transportdevices are coupled to opposite sides of the respective cart when thatcart is being transported between the central support position and itssecondary position.